Dryer with vacuum bar sheet feeder



7 WROVERL'Y ETA]. 3,359,648

DRYER WITH VACUUM BAR SHEET FEEDER Filed April 5, 1965 2 Sheets-Sheet 1 v L 8O n I 7 E INUENTORS I i" WILL/HM fi. OI/EELY V 64- JoH/v M F2057 30 M MFM.

ATTORNEYS Dec. 26, 1967 W.F.OVERLY ETAL 3,35 8

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ATTO2NEY5 United States Patent poration of Wisconsin Filed Apr. 5, 1965, Ser. No. 445,356 12 Claims. (Cl. 34-160) This invention relates to a sheet feeder using a chain having vacuum bars for holding the sheets.

The invention contemplates that the sheets will be fed through a dryer of a type in which the sheets are subjected to heat and rapidly moving air. It is important that the sheets be held fiat on the endless conveyor which propels them through the dryer and the invention is particularly concerned with a means whereby hollow conveyor bars having apertured sheet-engaging faces can be connected with a vacuum box which may be either above or below the bars in the path of movement of the bars and the work the conveyor advances.

Whether the vacuum box is above or below that portion of the conveyor path in which evacuation of the bars is required, it is preferred to use separate boxes adjacent the respective ends of the bars and to provide for a loose bearing lap of flanges on the bars with respect to flanges or side walls with which the vacuum boxes are respectively provided. The withdrawal of air through the vacuum boxes is sufliciently rapid so that the desired effect can be achieved regardless of leakage, even though the leakage may be substantial.

The vacuum bars are connected at their ends with conventional chains which operate over sprockets in the usual manner. Because the bars have thickness which greatly exceeds the thickness of the links of the chain, it is necessary to allow for relative movement between the bars as the chains pass around the sprockets. Particularly if the vacuum boxes are below the bars in the area in which the vacuum holds the work sheets to the conveyor, it is also necessary to provide some sort of closure between bars and this closure must allow for the relative movement of the bars as they pass around the sprockets with the chains.

Rotatable means is also provided for cooling the work immediately after it issues from the dryer.

In the drawings:

FIG. 1 is a diagrammatic view in side elevation of a dryer in which the invention is incorporated.

FIG. 2 is an enlarged fragmentary detail view in longitudinal section through a portion of the dryer and a portion of the vacuum box and a portion of the conveyor, parts being broken away and other parts of the conveyor being shown in elevation.

FIG. 3 is a detail view taken in section on the line 3-3 of FIG. 2.

FIG. 4 is a fragmentary detail view showing a portion of the conveyor in inverted plan.

FIG. 5 is a fragmentary detail view of the conveyor in plan, the pattern of vacuum openings being fragmentarily illustrated.

FIG. 6 is an enlarged fragmentary detail view of a single bar having a modified pattern of opening.

FIG. 7 is a fragmentary detail view in cross section through a modified arrangement in which the vacuum box is above the conveyor bars.

FIG. 8 is a frgamentary detail view taken on line 88 of FIG. 7.

FIG. 9 is a view taken in cross section on the line 9-9 of FIG. 10 through a roll to which the sheets are delivered from the conveyor.

FIG. 10 is a fragmentary view of the said roll taken in section on the line 10'10 of FIG. 9.

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It will be understood that the invention is usable wherever sheets are to be conveyed, the disclosure herein of a dryer being illustrative of an appropriate usage.

The dryer chamber 12 is of a type in which hot air supplied through pipe 14 is discharged through the nozzles 16, each of which has a terminal delivery slot which is continuous transversely of the work to be dried. Between the nozzles there are spaces 18 which communicate with outlet pipe 20 for carrying off the air and the moisture picked up thereby from the work.

The work sheets 22 can conveniently be supplied by roll 24 to the conveyor 26 which supports the Work sheets as they pass beneath the drying chamber 12 and its nozzles 16. Conveyor 26 will be described in detail later. For the present, it is desired merely to note that it comprises transversely extending vacuum bars 30. The groups in which the vacuum bars are arranged are of sufiicient length to receive the work sheets 22. These groups are defined by solid bars 32 intervening between the vacum bars and upon which conventional grippers are disposed to receive and hold the forward margins of the respective work sheets. These grippers pull the work sheets through the dryer and it is the function of the vacuum bars to hold the work sheets fiat so that they can not be displaced by the air blasts directed upon them through the nozzles 16 or by the partial vacuum involved in the withdrawal of the moisture through the spaces 18 and pipe 20.

The grippers on the conveyor 26 are in axially staggered relation to grippers 36 provided on the periphery of a chill roll 38. From roll 38, the sheet passes in turn to roll 40 which also has grippers at 42. Thence the sheet is advanced by conveyor 48 until, at the delivery point, the forward gripper 46 releases successive sheets to drop them on the pile 50.

The application of vacuum to hold the sheets to the conveyor 26 will now be described.

In the preferred arrangement shown in FIGS. 2 to 5, the conveyor 26 comprises laterally spaced endless flexible supports such as chains 52 operating over conventional sprockets such as are indicated at 54 and 56 in FIGS. 1 and 2. Beneath the drying chamber, the chains normally have a rectilinear path of travel as shown. At intervals, there are arms 58 projecting inwardly from each chain as best shown in FIG. 3, to which the respective vacuum bars 30 are bolted through spacers 60 to locate the apertured top surfaces 62 of the respective bars substantially on the center lines of the respective chains as clearly appears in FIG. 3. The foraminous top surfaces are in a common plane in the rectilinear run of the conveyor and are contiguous to provide a nearly continuous work-supporting surface to which the work is held by vacuum.

Each of the bars 30 is hollow and each is trapezoidal in cross section as shown in FIG. 2. The top surfaces 62 are proximate to provide substantially continuous support for the work sheets. From the top surfaces 62 of the respective bars, the side walls 64 converge inwardly so that as the chains 52 pass about the sprockets the top surfaces 62 of the respective bars will retain their proximate position but the respective walls 64 of each bar Will approach parallelism with and substantial face contact with the side walls of the next consecutive bars on the conveyor. This clearly appears in FIG. 2.

'Each of the vacuum bars 30 has end closures 66 and a bottom wall 68 which is closed except for the ports or openings through which air is withdrawn to subject the bar and the work to vacuum.

At each side of the path of the conveyor are vacuum manifolds 70. One will be sufficient in many cases but for bars of the length illustrated it is preferred to have at least two such vacuum manifolds. These manifolds are elongated boxes provided at appropriate points with a pipe or pipes 72 through which the air is withdrawn. The

upper margins of the side walls of the manifold 70 are open to provide an elongated port for communication with the ports of the respective bars 30 which are passing thereover. The bottom 68 of each vacuum bar is desirably provided with downturned flanges at 76 which, as clearly shown in FIG. 3, extend over the margins 74 into loose bearing engagement with the inner faces of the side walls of the flange boxes or manifolds 70.

Because the bars have to be spaced along their lower margins to enable them to pass around the sprockets 54 as above described, it is necessary to insert between the vacuum bars fillers 80 which span the spaces between bars to close the vacuum box openings in those areas. The fillers 80 have depending flanges S2 loosely fitting between the flanges 76 of the respective bars and of such length that each of the filler flanges 82 laps to some extent the flanges 76 of consecutive bars as best shown in FIG. 4. A loose seal is provided by upstanding flanges 84 mounted interiorly on the sides of the vacuum box 70 as illustrated in FIG. 3.

The respective closures or fillers 80 are held in position by upstanding flanges 86, each of which is riveted or welded to the side wall 64 of one of the bars. At its other side, there is a free upstanding flange 88 which is normally engaged with the lower margin of a side wall 64 of the next consecutive bar but is free of connection therewith to permit relative movement as the conveyor passes around sprockets 54 and 56. See FIG. 2. As already stated, no tight seal is required because the vacuum drawn can be made entirely adequate to hold the work sheets 22 to the conveyor even though the seal is far from perfect.

The drum 38 is chilled and serves to set the ink (if the drying of ink is the function of the drying mechanism). Its peripheral wall 90 is interrupted at one or more points, wherever the grippers 36 are provided. Within each seg ment of the outer peripheral wall 90 is an inner peripheral wall 92 which is connected therewith to provide a segmental cooling chamber 94. At one end each chamber communicates through a radial pipe 96 with the bore 98 in drum shaft 100, such bore being supplied with a chilling fluid through the supply line 102. At the other end of the drum, each of the chambers 94- communicates through a radial pipe 104 with a bore 106- at the other end of the drum shaft 100, bore 106 communicating with an exhaust line 108 for the cooling fluid.

Work sheets 22 are held to the drum 38 by the propelling grippers 36 which engage their respective forward margins but they are required to conform in face contact with the peripheral walls 90 of the drum by means of a retaining apron or belt 110 which encircles the drum between guide pulleys.

The apertures 116 in the foraminous top wall 62 of each bar 30 may be circular and arranged in rectangular patterns as best shown in FIG. 5. Alternatively, they may be elongated obliquely as shown at 11$ in FIG. 6. In any event, they will be suflicient in number and distribution so that the vacuum communicated therethrough to the under surface of the work sheet 22 will hold the work sheet securely to the contiguous top surfaces 62 of the several bars. These surfaces are all in one plane throughout the drying zone beneath housing 12. The endless flexible supports may be of any desired type. Instead of wire ropes it is preferred to use the chains 52 already described. The described sprockets, one of which is driven by power, exemplify guides about which the endless supports are trained. The showing is diagrammatic.

The vacuum bars may, if desired, be heated by a gas or other heater 122 supplied with fuel by pipe 124. The purpose of such a heater is to drive off condensate and alsoto keep the vacuum bars warm enough so that they will not detract from the functioning of the dryer.

The vacuum box means 700 may be above rather than below the bars. This is shown in FIGS. 7 and 8. If they are above the bars, then the bottom walls 680 of the respective bars 300 will be completely closed and the ports 4 or openings for communication with the box means will be provided in the top wall 62. The flanges 176 of the respective bars will now project upwardly to lap the inner side surfaces of the box means 700' as clearly appears in FIG. 7, and the seal members 184 will project downwardly.

As in the construction originally described, the flexible support means 52 has a horizontal run beneath the dryer in order that the contiguous top walls 62 of the several hollow bars will lie in one plane throughout this area. The principal difference consists in the elimina tion of the fillers 80. These are not required in the construction of FIGS. 7 and 8 because the walls 62 in which the ports or openings 120 are formed are already contiguous and therefore there is little or no leakage of air between them into the vacuum box 700.

In each of the constructions disclosed, the pipes 72 leading from the vacuum box (and which will normally be connected with an exhaust fan) may be regarded for the purposes hereof as the means for subjecting the vacuum box and bar to sub-atmospheric pressure for holding the work to the conveyor.

We claim:

1. In a dryer for sheet stock, the combination with a drying device including means for directing a drying gas upon sheets to be dried, of a conveyor having a run extending substantially rectilinearly and in close proximity beneath said device, said conveyor comprising a series of separate rigid hollow bars having foraminous sheetsupporting top surfaces which are closely adjacent and substantially in a common plane in said run, and means for evacuating said bars as they traverse said run whereby to hold sheets to said foraminous top surfaces.

2. A dryer according to claim 1 in which the several bars are arranged in mutually spaced groups in said conveyor, the conveyor including gripper bars in advance of each group and in the space following the preceding group, the gripper bars being provided with work sheet gripper means.

3. A sheet conveyor comprising the combination with laterally spaced flexible endless support means, of transverse hollow bars mounted at their ends upon the support means and having contiguous apertured work-supporting portions for sheets to be conveyed, and vacuum box means extending along the path of movement of said bars with said flexible means, said vacuum box means and bars having complementary openings providing communication of respective bars with said box means, and means for withdrawing air from said box means and successive bars communicating therewith whereby to create a partial vacuum in said communicating bars for holding sheets thereto, the respective bars having side wall portions which converge downwardly below the level of said flexible means, the flexible means having guides defining an endless path and the downward convergence of the sides of said bars accommodating relative movement of said bars in traversing said guides.

4. A conveyor according to claim 3 in which the box means is below the bars and a filler plate intervenes between each bar and the successive bar and covers the opening in said box means as each such opening is traversed by the space between bars.

5. A conveyor according to claim 3 in which the box means is above the bars, the contiguous work-supporting portions of the bars provided with their said openings being substantially continuous between the box openings aforesaid.

6. A conveyor according to claim 3 in which respective bars and said box means have complementary lapping flanges at least partially sealing the communicating openings between respective bars and said box means in the course of relative movement between the bars and box means.

7. A sheet conveyor comprising the combination with laterally spaced endless flexible support means and guides upon which said support means are mounted for circuitous movement in an endless path, said guides being spaced whereby a part of said path is substantially rectilinear, of hollow bars extending transversely between said support means and mounted thereon, said bars having contiguous foraminous top surfaces substantially at the level of said support means and having side walls downwardly converging toward each other beneath said surfaces and having bottom walls and end walls, a vacuum box extending longitudinally adjacent one of said support means and along which a wall of each successive bar moves during the operation of said support means, laterally spaced flanges on the respective bars and on the box in mutually lapping relation, said bars and box having openings between their respective flanges which are in substantial registration during the operation of the conveyor for placing the bars in communication with the box for holding sheets to said bars.

8. In a dryer, the combination with a drying device for sheets of material, of a conveyor for supporting and holding flat the sheets to be dried as they pass beneath the dryer, said conveyor including longitudinally spaced guides, endless flexible support means laterally spaced and mounted on the guides, said support means having runs which are substantially rectilinear beneath said device, said conveyor including transversely extending vacuum bars mounted at their ends upon respective guides and having contiguous foraminous top surfaces substantially in a common plane and approximately at the level of said support means, each of said bars having wall portions defining an interior cavity and including side walls converging downwardly from said foraminous surfaces to accommodate angular relative displacement of successive bars as they pass about said guides, and means for exhausting air from said bars as they pass beneath said device whereby to establish partial vacuum within respec tive bars communicated through the foraminous top surfaces thereof to hold work sheets to said surfaces.

9. A dryer according to claim 8 in which the means for withdrawing air from said bars comprises a vacuum box extending along the path of movement of said bars beneath said device, said vacuum box and bars having complementary ports which are in registry during the advancing movement of said bars.

10. A dryer according to claim 9 in which the vacuum box and bars further have mutually lapping flanges laterally bordering their respective ports whereby to provide at least partial seal about said ports.

11. A dryer according to claim 9 in which the vacuurn box is disposed beneath the bars, the bars being of generally trapezoidal form in cross section and the lower walls thereof being of lesser extent longitudinally of the path of conveyor movement than the foraminous walls aforesaid, the conveyor further including filler plates each connected with one of said bars and extending across the space between the lower wall of the last mentioned bar and the lower wall of a consecutive bar in the conveyor whereby to cover in the course of conveyor movement that portion of the port of the vacuum box which would otherwise be exposed between bars.

12. The dryer of claim 9 in which the vacuum box is above the conveyor bars and the ports with which the bars are provided and which register with the port of said box are in the foraminous top walls of the respective bars.

References Cited UNITED STATES PATENTS 557,056 3/1896 Dejonge 1981 19 X 1,613,445 1/1927 Davis et al 34-162 X 2,131,257 9/1938 Risley 34-62 X 2,138,178 11/1938 Lang 34-162 2,797,899 7/1957 Funk et a1 -89 X 2,969,869 1/ 1961 Klingler 271-74 X 3,060,595 10/1962 Dapses 34160 3,182,998 5/ 1965 Peterson 271-74 3,185,284 5/1965 Molins 271-74 X 3,192,648 7/1965 Seedorf 34-151 X FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner. 

1. IN A DRYER FOR SHEET STOCK, THE COMBINATION WITH A DRYING DEVICE INCLUDING MEANS FOR DIRECTING A DRYING GAS UPON SHEETS TO BE DRIED, OF A CONVEYOR HAVING A RUN EXTENDING SUBSTANTIALLY RECTILINEARLY AND IN CLOSE PROXIMITY BENEATH SAID DEVICE, SAID CONVEYOR COMPRISING A SERIES OF SEPARATE RIGID HOLLOW BARS HAVING FORAMINOUS SHEETSUPPORTING TOP SURFACES WHICH ARE CLOSELY ADJACENT AND SUBSTANTIALLY IN A COMMON PLANE IN SAID RUN, AND MEANS FOR EVACUATING SAID BARS AS THEY TRAVERSE SAID RUN WHEREBY TO HOLD SHEETS TO SAID FORAMINOUS TOP SURFACES. 